Degradable piezoelectric KNN/PLLA nanofibers for promoting osteogenesis and angiogenesis in bone regeneration

Replicating the endogenous electromechanical microenvironment of bone remains a significant challenge in regenerative medicine. This study aims to develop a promising scaffold by integrating piezoelectric K_0.5Na_0.5NbO₃/poly (KNN) nanoparticles into poly (L-lactic acid) (PLLA) nanofibers to promote bone healing.

KNN/PLLA nanofibers were electrospun and verified via X-ray diffraction (XRD). Scanning Electron Microscope (SEM) was used to characterize morphology and assess biocompatibility on 9 wt% KNN/PLLA. The distribution of KNN was analyzed via energy dispersive spectroscopy (EDS). The mechanical properties were evaluated through Universal Testing Machine (UTM). Piezoelectric properties were quantified using an electrostatic voltmeter and Piezoresponse Force Microscopy (PFM), while Niobium (Nb) ion release was measured via inductively coupled plasma (ICP) analysis. Osteogenic differentiation was evaluated through cell proliferation, quantitative real-time PCR (qRT-PCR) for osteogenic markers osteocalcin (OCN) and runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP) and Alizarin Red S (ARS) assays for osteogenesis, and tube formation for angiogenesis.

XRD confirmed successful KNN loading. Tensile tests showed that KNN incorporation enhanced mechanical properties. ICP analysis detected Nb release, reflecting the degradation. Increasing KNN content reduced fiber diameter and enhanced piezoelectricity. SEM verified biocompatibility via cell growth on 9 wt% KNN. Notably, KNN loading dose dependently upregulated OCN and RUNX2 expression, enhanced ALP activity and ARS staining, and promoted angiogenesis.

The 9 wt% KNN/PLLA nanofibers exhibited superior physicochemical and mechanical properties, a sevenfold increase in piezoelectric output. The nanofibers significantly enhanced bone regeneration, evidenced by upregulated osteogenic markers (OCN/RUNX2) and markedly improved ALP activity (60%) and ARS mineralization (70%). Coupled with favorable degradation and enhanced angiogenesis, the nanofibers demonstrate high potential for functional bone tissue engineering.